Choice
of feed outlet is crucial for making sure all roots are adequately fed.
The choice will depend upon system type,
system volume and flow rate requirement (etc).
1. Bare hose end: Blockages are
least likely. This is the preferable method for NFT, or any system where
the outlet flow does not need to be sprayed (dispersed) or tightly
regulated. Flow rate is adjustable via an in-line tap.
2. Flood & Drain: Specific to ‘Flood
& Drain’ systems.
3. Drippers (typically used for
run-to-waste):
+ “Pressure compensating” drippers
deliver a preset flow rate (Fig 6.18). These are ideal for run-to-waste
systems for obtaining a specific percentage run-off (see
Table 6.1).
+ “Adjustable” drippers permit the flow
rate to be adjusted. However, because these are non pressure compensating,
their output will vary with delivery pressure.
NOTE: Drippers are prone
to blocking therefore make sure they can be dismantled for routine
cleaning (Fig 6.18b).
4. Sprayers / Jets: (Fig 6.19)
Use these when top-feeding to achieve an even distribution of nutrient
over the surface of pots (Fig
5.10). However note, they are prone to blockages, and will increase
evaporation losses and salt build up.
